Risk factors for ventral luxation in canine total hip replacement.

OBJECTIVE

To identify risk factors associated with ventral luxation (VL) of canine total hip replacement (THR), and outcome.

STUDY DESIGN

Retrospective study.

ANIMALS

Dogs (n=602) that had THR (563 cemented, 35 cementless, 4 hybrid).

METHODS

Dogs (1999-2004) with VL after THR were compared with dogs with uncomplicated THR. Data included signalment, body weight, diagnosis, implant size, acetabular cup orientation, and femoral displacement ratio (FDR).

RESULTS

VL was diagnosed in 11 (1.8%) dogs after primary THR. Including 2 other dogs that had VL after the study period, 10 (77%) of 13 dogs had VL within 7 days of surgery. Risk factors for VL included Saint Bernard-type dogs (P=.0001), short neck extension (P=.0005), and high angle of lateral opening in other breeds (P=.018). There were trends toward higher risk of VL with lower FDR in Saint Bernard types (P=.060), and with cementless implants (P=.061). Twelve dogs had revision arthroplasty that was successful in all cementless and 2 cemented VL cases. Five dogs had recurrent VL and a poor outcome.

CONCLUSION

VL is generally an early complication of THR, with no single common risk factor identified.

CLINICAL RELEVANCE

Saint Bernard types and short neck extensions are associated with increased risk of VL. Poor cup orientation is a determining factor for VL in some dogs, but a protective orientation of the acetabular cup was not found. Revision is successful in most dogs, but recurrent VL merits a guarded prognosis.